High-throughput workpiece handling

ABSTRACT

A system and method for receiving unprocessed workpieces, moving them, orienting them and placing them in a load lock, or other end point is disclosed. The system includes a gantry module for moving workpieces from a conveyor system to a swap module. The swap module is used to remove a carrier or matrix of processed workpieces from a load lock and place a carrier of matrix of unprocessed workpieces in its place. The processed workpieces are then moved by the gantry module back to the conveyor. The gantry module may have X, Y, Z and rotational actuators and include an end effector having multiple grippers. A method of aligning a plurality of workpieces on the end effector so that the plurality can be transported at the same time is also disclosed.

This application claims priority of U.S. Provisional Patent ApplicationSer. No. 61/554,715, filed Nov. 2, 2011, the disclosure of which isincorporated herein in its entirety.

FIELD

This invention relates to workpiece handling and, more particularly, toworkpiece handling for high-throughput applications.

BACKGROUND

Ion implantation is a standard technique for introducingconductivity-altering impurities into a workpiece. A desired impuritymaterial is ionized in an ion source, the ions are accelerated to forman ion beam of prescribed energy, and the ion beam is directed at thesurface of the workpiece. The energetic ions in the beam penetrate intothe bulk of the workpiece material and are embedded into the crystallinelattice of the workpiece material to form a region of desiredconductivity.

Ion implantation has been demonstrated as a viable method to dope solarcells. Two concerns of the solar cell manufacturing industry aremanufacturing throughput and cell efficiency. Cell efficiency measuresthe amount of energy converted into electricity. Higher cellefficiencies may be needed to stay competitive in the solar cellmanufacturing industry. However, manufacturing throughput cannot besacrificed in order to increase cell efficiency.

Use of ion implantation removes process steps needed for existing solarcell technology, such as diffusion furnaces. For example, a laser edgeisolation step may be removed if ion implantation is used instead offurnace diffusion because ion implantation will only dope the desiredsurface. Ion implantation also offers the ability to perform a blanketimplant of an entire surface of a solar cell or a selective (orpatterned) implant of only part of the solar cell. Selectiveimplantation at high throughputs using ion implantation avoids thecostly and time-consuming lithography or patterning steps used forfurnace diffusion. Selective implantation also enables new solar celldesigns. Furthermore, ion implantation has been used make solar cellswith higher cell efficiencies.

Therefore, any improvement to manufacturing throughput of an ionimplanter or its reliability would be beneficial to solar cellmanufacturers worldwide. This may accelerate the adoption of solar cellsas an alternative energy source.

SUMMARY

A system and method for receiving unprocessed workpieces, moving them,orienting them and placing them in a load lock, or other end point isdisclosed. The system includes a gantry module for moving workpiecesfrom a conveyor system to a swap module. The swap module is used toremove a carrier or matrix of processed workpieces from a load lock andplace a carrier of matrix of unprocessed workpieces in its place. Theprocessed workpieces are then moved by the gantry module back to theconveyor. The gantry module may have X, Y, Z and rotational actuatorsand include an end effector having multiple grippers. A method ofaligning a plurality of workpieces on the end effector so that theplurality can be transported at the same time is also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present disclosure, reference is madeto the accompanying drawings, which are incorporated herein by referenceand in which:

FIG. 1 is a perspective view of a first embodiment of a workpiecehandling system;

FIG. 2 is a top perspective view of the first embodiment of a workpiecehandling system illustrated in FIG. 1;

FIG. 3 is a side perspective view of the first embodiment of a workpiecehandling system illustrated in FIG. 1;

FIGS. 4A-E illustrate one embodiment of workpiece handling using theworkpiece handling system illustrated in FIGS. 1-3;

FIGS. 5A-F illustrate another embodiment of workpiece handling using theworkpiece handling system illustrated in FIGS. 1-3;

FIG. 6 is an embodiment of a gantry module as illustrated in FIG. 1;

FIGS. 7A-E illustrate an embodiment of workpiece handling using theworkpiece handling system illustrated in FIG. 6;

FIG. 8 is a flow chart showing a method of picking up workpieces usingthe gantry module of FIG. 6;

FIG. 9 is an embodiment of a swap module as illustrated in FIG. 1;

FIG. 10 is a second embodiment of an end effector for use with a swapmodule as illustrated in FIG. 1;

FIGS. 11A-C show the placement of workpieces in a load lock using theend effector of FIG. 10; and

FIG. 12 shows a configuration using two workpiece handling systems.

DETAILED DESCRIPTION

The workpiece handling system herein is described in connection withsolar cell workpieces. However, the embodiments can be used with otherworkpieces such as semiconductor wafers, light emitting diodes (LEDs),silicon-on-insulator (SOI) wafers, or other devices. The workpiecehandling system can be used with ion implanters or with other processingequipment like deposition, etching, or other workpiece processingsystems. Thus, the invention is not limited to the specific embodimentsdescribed below.

The exemplary workpiece handling system 100 illustrated in FIGS. 1-3 maybe capable of processing greater than approximately 2000 wafers per hour(wph) using a 4×4 matrix of workpieces. Of course, other workpiecematrix designs may be used and the embodiments herein are not limitedmerely to a 4×4 matrix. A 2×2 or 2×4 matrix also may be used. Thesefigures represent the workpiece handling system, the individualcomponents of which will be described in more detail below. FIG. 1 showsa perspective view of the belt modules, gantry module, matrix, buildstation, swapbot and load locks. FIGS. 2 and 3 show a top view and sideview of these components, respectively.

This matrix 101 of workpieces may be placed in a carrier that hasindividual slots or depressions to hold workpieces. In an alternateembodiment, no carrier is used for the workpieces. The matrix 101instead is handled by robots or other means before and duringprocessing. The matrix in this instance may be held on an electrostaticor mechanical clamp, or by gravity.

This workpiece handling system 100 transfers workpieces from a cassetteor other interface, builds the matrix 101, and moves the matrix 101 intothe load lock 102. The reverse process also may be performed by theworkpiece handling system 100 to transfer workpieces back to thecassette or other interface. The load lock 102 is connected to an ionimplanter or some other processing tool.

In this embodiment, three belt modules 106 a-c may transport theworkpieces from the cassette. The transport of the workpieces may beperformed at a specified speed, interval, or pitch. A robot may be usedto place the workpieces onto the belt modules 106 a-c. At the end of thebelt modules 106 a-c, a camera 107 and a controller will determine theposition of each of the workpieces and will determine if the position ororientation of the workpieces needs to be corrected during the transferto the matrix 101. More or less than three belt modules 106 a-c may beused in other embodiments. Each of these belt modules 106 a-c may bedesignated for load or unload of workpieces or may be used for bothloading and unloading.

A gantry module 108 picks workpieces from the belt modules 106 a-c andbuilds the matrix 101, such as using electrostatic, mechanical, orvacuum forces. The gantry module 108 may move in three-dimensions andmay also achieve rotational motion. This gantry module 108 may useinformation from the camera 107 and controller to correct the positionor orientation of the workpieces. The gantry module 108 also may removeworkpieces from the matrix 101 to places onto the belt modules 106 a-cfor transfer back to the cassette or other interface.

The gantry module 108 may have at least one y-axis actuator, one x-axisactuator, one z-axis actuator, and a tilt, or rotational, actuator. Thisprovides four degrees of freedom and enables pick-and-place operation.The gantry module 108 can correct the workpieces in the x, y, and θ(tilt) directions. The gantry module 108 also can transport theworkpieces from any of the belt modules 106 a-c to any of the positionsin the matrix 101. Rotation or tilting in the 0 direction may beperformed by the gantry module 108.

In an alternate embodiment, the gantry module 108 can skip or not place“bad” workpieces. These “bad” workpieces may be damaged or broken. Thegantry module 108 also may compensate for “missing” workpieces that maynot have properly loaded onto the belt modules 106 a-c. The camera 107and a processor may be used to assist the gantry module 108 in thisregard.

The end effector 105 of the gantry module 108 is a multi-gripper designthat may be a smaller version of the matrix 101. Thus, while the matrix101 may be 4×4 workpieces, the gantry module 108 may be 1×4 or someother design. The workpieces may be corrected by the gantry module 108either individually or as a 1×4 group.

In one embodiment of operation, the gantry module 108 will take fourworkpieces that have been processed and place these on one of the beltmodules 106 a-c. The gantry module then takes four unprocessedworkpieces from the belt modules 106 a-c and places these in the matrix101. This reduces the amount of travel time and the time that the gantrymodule 108 is not transporting workpieces. The unprocessed workpiecesare placed in the matrix 101 where the previously processed workpieceswere removed from. This process may be repeated and the combined loadand unload of the matrix 101 by the gantry module 108 may be used forthe entire matrix 101. Of course, the gantry module 108 may fully unloadthe matrix 101 before placing unprocessed workpiece on the matrix 101.

A swap module 109 (using at least one “swap robot” or “swapbot”) may beused to place the matrix 101 into the load lock 102. This swap module109 may be a linear actuator. There may be one or more than one swaprobots in the swap module 109. These may, for example, hold an emptycarrier and a full carrier. One swap robot may be parked out of the wayduring loading and unloading. Each swap robot may have a z-axis actuatorand one or more y-axis actuators for each of the blades. The first swaprobot may pick up unprocessed workpieces in the matrix 101 from thebuild station 110 and the second swap robot may extend into the loadlock 102 to pick up processed workpieces. The processed workpieces areremoved from the load lock 102 and the unprocessed workpieces are placedin the load lock 102. The processed workpieces are returned to the buildstation for unloading while the unprocessed workpieces are implanted orotherwise processed.

The building of the matrix 101 may be coordinated with the pumping downor venting of the load lock 102. This may increase throughput of thesystem attached to the load lock 102, such as an ion implanter.

FIG. 6 shows an expanded view of the gantry module 108. The gantrymodule 108 has two rails, or Y actuators 120 a-b, on which a crossbar,or X actuator 121, moves. In some embodiments, a servo motor 122 ispositioned on one of the Y actuators 120 b with a gear box 123 and adrive shaft 124. The rotation of the servo motor 122 causescorresponding rotation in the drive shaft 124, which, in turn, causes Xactuator 121 to move. The robot head 125 is located on the X actuator121. Through movement of the Y actuators 120 a-b and X actuator 121, therobot head 125 may move in the X and Y directions. The robot head 125also has a Z actuator 126, which allows the robot head 125 to move upand down as necessary.

The robot head 125 also has an end effector 128. In some embodiments,the end effector 128 may include a plurality of grippers 129 at itsdistal end. The grippers 129 may use any suitable system for picking upand holding the workpieces, including but not limited to Venturidevice-based suction systems and vacuum systems. In some embodiments,the suction to each gripper 129 is separately controlled such that onegripper may be picking up or holding a workpiece, while another gripperis inactive. These grippers 129 may be arranged in any configuration,such as a 1 x 4 linear array as shown in FIG. 6. In some embodiments,such as that shown in FIG. 6, the end effector 128 may have the abilityto rotate about the Z axis, where this rotation is described as tilt or0 axis rotation in this disclosure. This rotational actuator allows theend effector (and the plurality of grippers) to be rotated as describedin more detail with respect to FIG. 7.

In another embodiment, rather than, or in addition to using a commonrotational actuator to rotate the entire end effector 128, individualrotational actuators are located on the end effector 128, such that eachgripper may be independently rotated.

The gantry module 108 also has a controller (not shown), which controlsthe movements of the various actuators and grippers. Of course, morethan one controller can also be used if desired. The controller includesa processing unit, a storage element and an input/output module. Thestorage element contains instructions which allow the gantry module 108to execute the sequences described herein, as well as any other desiredmovements.

Having described the structural components of the gantry module 108, itsoperation will be described. FIGS. 4A-E illustrate one embodiment ofworkpiece handling using the workpiece handling system illustrated inFIGS. 1-3. In FIG. 4A, the end effector 128, which may be part of thegantry module 108 of FIG. 6, is positioned over a first belt module 106c. This is done by moving the X actuator 121 and the Y actuators 120a-b, as described above.

At this time, the matrix 101 may contain sixteen processed workpieces201 in a 4×4 arrangement. Other arrangements may also within the scopeof the disclosure. One belt module, in this instance belt module 106 a,contains unprocessed workpieces 202 (shaded in the embodiment of FIG.4A).

In FIG. 4B, the gantry robot head, and specifically, the end effector128, is moved from its previous position and is positioned over thematrix 101. The end effector 128 then picks up four processed workpieces201 from a row of the matrix 101. The gantry module 108 may correct theposition or tilt of the processed workpieces 201 after these have beengripped or picked up. In other embodiments, the gantry module 108corrects the position or tilt of the workpieces before they are pickedup. For example, in one embodiment, the gantry module 108 uses camera107 to determine the tilt of a first processed workpiece 201 a. It may,for instance, determine that the workpiece 201 a is rotated 2°clockwise. The gantry module 108 will, in response to this, actuate therotational actuator in the robot head 125 to rotate the end effector 128by 2°. The end effector 128 will then pick up the processed workpiece201 a. The gantry module 108 will then utilize the camera 107 (as seenin FIG. 1) to determine the position and tilt of the second processedworkpiece 201 b. The gantry module 108 will then rotate the endeffector, which is holding processed workpiece 201 a, to align withprocessed workpiece 201 b. Once aligned, the end effector will pick upthe second processed workpiece 201 b. The gantry module 108 may repeatthis sequence until all process workpieces are picked up by the endeffector 128.

In FIG. 4C, the gantry robot 200 has transported the four processedworkpieces 201 to one of the belt modules, in this case belt module 106c for unloading. In the case where the processed workpieces were alignedas they were picked up, the end effector simply places the processedworkpieces 201 on the belt module 106 c. In another embodiment, thegantry module 107 does not align the processed workpieces 201 as theyare picked up, and performs the alignment procedure described above asthe processed workpieces 201 are placed. In yet other embodiments, thealignment procedure is not performed on processed workpieces 201, as itis assumed that these were previously aligned by the gantry module 108when they were original placed in the carrier.

In FIG. 4D, the gantry module 108, after placing processed workpieces201, positions the end effector 128 over the unprocessed workpieces 202and picks these up. The unprocessed workpieces 202 may be crooked orpositioned incorrectly due to errors in unloading from the cassette orother interface. In some embodiments, the gantry module 108 may correctthe position or tilt of the unprocessed workpieces 202 after these havebeen gripped or picked up. In other embodiments, the gantry module 108aligns the unprocessed workpieces 202 individually as they are beingpicked up as described above. FIG. 8 shows a flowchart of the procedureused to align workpieces as they are being picked up. Of course, thisprocedure is applicable to an end effector having an arbitrary number ofgrippers. The alignment can also be performed when the workpieces arebeing placed instead.

In FIG. 4E, the gantry module 107 moves the robot head and places thefour unprocessed workpieces 202 into the matrix 101. The unloadedprocessed workpieces 201 may have been removed to the cassette or otherinterface using one of the belt modules 106 a-c. More unprocessedworkpieces 202 may be loaded onto one of the belt modules 106 a-c. Thistransfer process is repeated until the processed workpieces 201 areunloaded from the matrix 101 and the unprocessed workpieces 202 havebeen loaded into the matrix 101.

The above description illustrates one benefit of the rotational actuatorthat allows rotary movement of the end effector, namely, the ability toalign workpieces as they are being picked up or placed. FIG. 7A-E showsanother benefit of the rotational actuator in the robot head 125. Inthis embodiment, the end effector 128, which may be part of the gantrymodule 108 of FIG. 6, transfers four processed workpieces 201 from thematrix 101 and places these four processed workpieces 201 on one of thebelt modules 106 a-c. However, the end effector 128 rotates 90° betweenthe picking up of the processed workpieces 201 from the matrix 101 andthe placing of those processed workpieces 201 on the belt module 106a-c, as shown in FIGS. 7B-7C. Similarly, the end effector 128 rotates90° (or −90°) when transferring unprocessed workpieces 202 from the beltmodules 106 a-c to the matrix 101, as shown in FIGS. 7D-7E. As before,alignment can be done as the workpieces are being picked up or placed,and this alignment may be performed at the belt module 106 a-c, at thematrix 101, or at both locations.

FIG. 12 shows a configuration using two workpiece handling systems 500a, 500 b. In this system, the two systems 500 a, 500 b each moveworkpieces to and from a respective load lock 510 a, 510 b. Workpiecesare then moved from the load locks 510 a, 510 b to a transfer chamber520. Workpieces are transferred from the transfer chamber 520 to theprocess chamber 530.

The transfer chamber moves workpieces from one port to another byrotating the arm of a robot. Thus, workpieces that enter from load lock510 b are rotated 180° before entering the process chamber 530. However,note that the load lock 510 a is oriented at 90° with respect to loadlock 510 b. Thus, the robot only rotates workpieces from load lock 510 a90° before they enter the process chamber 530. Typically, the robotwithin the transfer chamber 520 is simple, comprising an arm thatrotates about a pivot point and which can be extended radially outwardinto the load locks 510 a, 510 b to pick up and deliver workpieces. Thearm is then be rotated about this pivot point, allowing it to deliverworkpieces to and from the process chamber 530. Rotation of workpiecesseparate from that which occur as a result of rotation about the pivotpoint is not typically possible. However, the process chamber 530expects that all workpieces are received in a single orientation.

Thus, if the orientation of workpieces from workpiece handling system500 a is to match the orientation of those from workpiece handlingsystem 500 b, these workpieces must be rotated by 90° relative to thosearriving from workpiece handling system 500 b. In other words, assumethat the robot in the transfer station 520 rotates clockwise. To insurea consistent orientation, workpieces from system 500 a may be rotatedclockwise 90° prior to entering the load lock 510 a. Alternatively,workpieces from system 500 b may be rotated 90° counterclockwise beforethey enter load lock 510 b. The rotational actuator of the gantry module107 allows either of these actions.

In another embodiment, rotational actuators are located on the endeffector, such that each gripper has an associated rotational actuator.This configuration may allow the alignment sequence shown in FIG. 8 tobe performed in parallel, such that all workpieces can be aligned by acorresponding gripper simultaneously, if the cells are pre-aligned withfunnels, bumpers and/or stops.

FIG. 9 shows an expanded view of the swap module 109. The swap module109 has two swap robots 300, 301. These swap robots 300, 301 maintain afixed spatial relationship with each other in the X and Z directions. Inother words, the swap robots 300, 301 have only one degree of freedombetween them, i.e. the Y direction. To accomplish this, the swap module109 has two Y actuators 310, 311, which are offset from each other inthe Z direction. These Y actuators 310, 311 have the capability to moveback and forth in the Y direction, irrespective of each other. In otherwords, Y actuator 310 may be in the front position, while the other Yactuator 311 is in the rear position (as shown in FIG. 9). Of course,both can be in the front position or both may be in the rear position.In these configurations, the swap robot 300 would be directly on top ofthe swap robot 301.

Each swap robot 300, 301 may have an end effector, which is linked to acarrier or can hold a matrix 101 of workpieces. The swap module 109 alsohas a Z actuator 320, which moves both Y actuators up and down inunison. The swap module 109 may also have a leveling device 330. Theleveling device 330 is used to insure that the end effectors are kepthorizontal.

The swap module 109 also has a controller (not shown), which controlsthe movements of the various actuators and end effectors. Of course,more than one controller can also be used if desired. The controllerincludes a processing unit, a storage element and an input/outputmodule. The storage element contains instructions which allow the swapmodule 109 to execute the sequences described herein, as well as anyother desired movements.

FIGS. 5A-F illustrate one embodiment of how the swap module 109cooperates with the load lock 102 and gantry module 108 to moveworkpieces. The first swap robot 300 and second swap robot 301 may bepart of the swap module 109 of FIGS. 1-3. It should be noted that, inone embodiment, the gantry module 108, and specifically the end effector128, moves workpieces to and from the swap module 109 directly. In otherwords, the gantry module 108 and the swap module 109 cooperate togetherto move the unprocessed workpieces from the belt modules 106 to the loadlock 102. The workpieces are transferred by the gantry module 108 fromthe belt modules 106 to the swap robot 300 or swap robot 301 without anintervening step, such as putting the workpieces on a static surface.The swap robots 300, 301 then move the workpieces to the load lock 102.

In FIG. 5A, the gantry robot 108, and specifically end effector 128 hasloaded unprocessed workpieces 202 on the first swap robot 300 from thebelt module 106. These unprocessed workpiece 202 may be in a 4×4 matrix,though only four are illustrated in the cross-section of FIG. 5A. Thefirst swap robot 300 and second swap robot 301 are lifted in FIG. 5Busing the Z actuator 320 (see FIG. 9). At this point, the second swaprobot 301, which is empty, extends into the load lock 102. The secondswap robot 301 removes processed workpieces 201 in FIG. 5C, which alsomay be in a 4×4 matrix. This action is performed using the Y actuator310 (see FIG. 9). The first swap robot 300 then places the unprocessedworkpieces 202 into the load lock 102. So that both swap robots 300, 301are able to access the load lock 102, the first swap robot 300 andsecond swap robot 301 may change vertical position during the loadingand unloading of the load lock 102 if it only has a single port. Thischange in vertical position is achieved through use of the Z actuator320. If the load lock 102 has multiple ports, then no vertical positionchange during loading and unloading may be required.

In FIG. 5D, the first swap robot 300 is parked out of the way. Thisparked position may be above the load lock 102, below the load lock 102,or in the case of two load locks 102, between the load locks 102. Thisenables the gantry robot 108, and specifically end effector 128, tounload the processed workpieces 201 from the second swap robot 300. Thegantry robot 108 also may load unprocessed workpieces on the second swaprobot 301. The first swap robot 300 will then be removed from the parkedposition, unload processed workpieces 201 from the load lock 102 as seenin FIG. 5E, and then the second swap robot 301 will place unprocessedworkpieces 202 into the load lock 102 as seen in FIG. 5F. The gantryrobot 200, and specifically end effector 128, will unload the processedworkpieces 201 from the first swap robot 300 and load unprocessedworkpieces 202 onto this first swap robot 300. Then the process then maybegin again as illustrated in FIG. 5A. The second swap robot 301 may beplaced in a parked position or may just remain disposed under the firstswap robot 300 during loading and unloading of the first swap robot 300.

There are several ways that the swap robots 300, 301 may join with thecarrier or matrix 101. In FIG. 9, the swap robots 300, 301 have endeffectors 340, 341, respectively. These end effectors 340, 341 have oneor more holes 350 passing through at least a portion of their bodies.These holes 350 are used to hold fingers 371, which extend from the endeffector 340, 341. In one embodiment, there are three fingers 371 a-c,with two fingers 371 a,c positioned so as to be slightly wider than thecarrier 101, and a third shorter finger 371 b located between these twoouter fingers. The carrier or matrix 101 has a main portion 370, whichis used to hold the workpieces. Fingers 371 a,c extend along the outeredges of main portion 370. In some embodiments, the fingers 371 a,c havea pin or other projection along their inner edge that is used to contactthe outer edge of main portion 370. In addition, shorter finger 371 bmay have a projection which is used to contact a third side of the mainportion 370 of the carrier 101. To place the workpieces within the loadlock 102, the end effector 340 with the carrier 101 is extended into theport. The end effector 340 is lowered such that the carrier or matrix101 touches the lower surface within the load lock 102. As the endeffector 340 is lowered slightly further, the projections no longercontact the main portion 370.

At this point, the end effector 340 can be moved horizontally away fromthe load lock 102, and the carrier or matrix 101 will remain in the loadlock 102. To join the end effector 340 with the carrier or matrix 101,the reverse operation is performed. The end effector 340 is extendedinto the load lock 102 below the level of the carrier main portion 370.The end effector 340 is extended until the projection on finger 371 b isin contact, or nearly in contact, with the front edge of the carrier370. The end effector 340 is then lifted. The projections along theinner edges of the fingers 371 a,c contact the outer sides of the mainportion 370, while the projection on the shorter finger 371 b contactsthe front side of the carrier 370. The end effector 340 is then furtherlifted, while elevates the carrier away from the load lock 102. The endeffector 340 can then be moved horizontally away from the load lock 102.

FIG. 10 shows another embodiment of an end effector 400. This endeffector 400 comprises a plurality of fingers 410 that are spaced apart.Unlike the fingers 371 of the previous embodiments, these fingers 410are used to hold workpieces thereon. Optionally located on each finger410 are one or more workpiece holders 420. In one embodiment, eachworkpiece holder 420 has a raised center portion 425, which isperpendicular to the dimension of the fingers 410, and two lower endportions 427, 428, one on each side of the raised center portion 425.The gantry module 108, and specifically the end effector 128, places theworkpiece such that its ends rest against the raised center portion 425of two adjacent workpiece holders 420. The workpiece holder 420 is usedto hold the one side of a first workpiece on one lower end portion 427,and the opposite side of the adjacent workpiece with the opposite lowerend portion 428, such that the two adjacent workpieces are separated bythe raised center portion 425. The raised center portion 425 is used toseparate the workpieces from each other and also serves to create anatural contour on which each workpiece rests so as to keep theworkpieces stable. The raised center portions 425 also can be used toalign the workpieces when the end effector 400 is accelerated duringwafer transfer and the workpieces are pressed against the raised centerportions 425.

FIGS. 11A-C show a top view of a load lock 102 used with the endeffector 400 of FIG. 10. The load lock 102 has a plurality of standoffs450 on which the workpieces 201 will rest. FIG. 11A shows an empty loadlock 102 with the standoffs 450. In FIG. 11B, the end effector 400 witheach of the fingers 410 having three workpieces 201 is moved into theload lock. The end effector 400 is then lowered such that each workpiece201 rests on several of the standoffs 450. The end effector 400 is thenremoved, as shown in FIG. 11C, and the workpieces 201 remain on thestandoffs 450.

In some embodiments, the standoffs 450 in the load lock 102 are spacedso as to correspond to the four corners of each workpiece (in the caseof rectangular workpieces), as shown in FIG. 11. In other embodiments,the load lock 102 is designed such that lower surface has a plurality ofslots. The fingers 410 pass through these slots in the lower surface ofthe load lock 102, and allow the workpieces to rest on that lowersurface.

In another embodiment, the lower surface of the load lock may havemovable pins. Thus, rather than having the end effector 400 move in thevertical direction as described above, the end effector 400 only movesin the horizontal direction. In this embodiment, the end effector 400enters the load lock 102 moving only in a horizontal direction. The pinswithin the lower surface of the load lock 102 are then upwardlyactuated. These pins move upward to contact the workpieces, therebyremoving them from the fingers 410. The end effector 400 can then bewithdrawn from the load lock by simply moving the end effector 400 inthe horizontal direction. The pins in the lock load 102 can then belowered if desired. To remove the workpieces, the pins in the load lock102 are fully extended. This lifts the workpieces from the lower surfaceof the load lock 102. The fingers 410 then enter the load lock 102 at alevel below the workpieces. The pins in the load lock 102 then retract,causing the workpieces to move downward until they rest on the fingers410.

The present disclosure is not to be limited in scope by the specificembodiments described herein. Indeed, other various embodiments of andmodifications to the present disclosure, in addition to those describedherein, will be apparent to those of ordinary skill in the art from theforegoing description and accompanying drawings. These other embodimentsand modifications are intended to fall within the scope of the presentdisclosure. Furthermore, although the present disclosure has beendescribed herein in the context of a particular implementation in aparticular environment for a particular purpose, those of ordinary skillin the art will recognize that its usefulness is not limited thereto andthat the present disclosure may be beneficially implemented in anynumber of environments for any number of purposes. Accordingly, theclaims set forth below should be construed in view of the full breadthand spirit of the present disclosure as described herein.

What is claimed is:
 1. A workpiece handling system, comprising a gantrymodule for moving a plurality of workpieces from a first location to asecond location, said gantry module comprising: an end effector havingone or more grippers for picking up said workpieces; a first actuator tomove said end effector in an X direction; a second actuator to move saidend effector in a Y direction; a third actuator to move said endeffector in a Z direction; and a rotational actuator to rotate said endeffector about said Z direction.
 2. The workpiece handling system ofclaim 1, wherein said grippers are in communication with a suctionsystem.
 3. The workpiece handling system of claim 1, further comprisinga swap module, said swap module comprising: two swap module endeffectors, each having an associated actuator to move said swap moduleend effector in said Y direction; and an actuator to move said two swapmodule end effectors in said Z direction, wherein a distance betweensaid two swap module end effectors in said Z direction remains constant.4. The workpiece handling system of claim 3, wherein said swap modulesend effectors are adapted to couple with a carrier, said carrier adaptedto store a plurality of workpieces.
 5. The workpiece handling system ofclaim 4, wherein said second location comprises said carrier.
 6. Theworkpiece handling system of claim 3, wherein said swap module endeffectors comprise a plurality of fingers, each of said fingers adaptedto support one or more workpieces.
 7. The workpiece handling system ofclaim 6, wherein said second location comprises said fingers.
 8. Theworkpiece handling system of claim 1, wherein said end effectorcomprises a plurality of linearly arranged grippers.
 9. A method ofhandling a plurality of workpieces from a source to a destination,comprising: using a gantry module to pick up a plurality of workpiecesfrom a first location and move said plurality of workpieces to a firstswap module end effector, said gantry module having an end effectorcapable of moving in x, y, and z directions and capable of rotatingabout said z direction; and using said swap module comprising: two swapmodule end effectors, wherein said swap modules move in said y and zdirections to load and unload said plurality of workpieces from saiddestination.
 10. The method of claim 9, wherein second swap module endeffector removes a second plurality of workpieces from said destinationprior to said first swap module end effector placing said plurality ofworkpieces at said destination.
 11. The method of claim 10, wherein saidend effector picks up said second plurality of workpieces from saidsecond swap module end effector and delivers them to a third location.12. The method of claim 11, wherein said first swap module is locatedabove said second swap module, and said first swap module is moved insaid y direction to a parked location to allow workpieces from saidsecond swap module to be accessed by said end effector.
 13. The methodof claim 12, wherein said destination comprises at least one load lockand said parked location is selected from a position above said loadlock, a position below said load lock, and a position between said loadlock and a second load lock.
 14. The method of claim 9, wherein said endeffector comprises a plurality of linearly arranged grippers and picksup a plurality of workpieces arranged along a first direction, andplaces said plurality of workpieces on said first swap module endeffector along a second direction, said second direction orthogonal tosaid first direction.
 15. The method of claim 9, whereby a carrier iscoupled to said first swap module end effector and said end effectorplaces said workpieces in said carrier.
 16. The method of claim 15,wherein said swap module end effector places said carrier at saiddestination.
 17. The method of claim 9, whereby said swap module endeffector comprises a plurality of fingers, and said end effector placessaid workpieces on said fingers.
 18. The method of claim 17, furthercomprising aligning each of said workpieces against a raised centerportion on each of said plurality of fingers when said swap module endeffector is moved in said y direction.
 19. The method of claim 9,wherein said end effector comprises a plurality of grippers and saidgantry module moves said end effector in said x, y, z directions androtates about said z direction to successively align each of saidworkpieces with a respective one of said plurality of grippers prior topicking up each of said workpieces.
 20. The method of claim 19, furthercomprising using a suction system to pick up one of said plurality ofworkpieces after said end effector is aligned to a respective one ofsaid plurality of grippers.
 21. A method of picking up a plurality ofworkpieces using a gantry module, said gantry module having an endeffector having a plurality of linearly arranged grippers for picking upsaid workpieces, said method comprising: using a camera to determine alocation of said plurality of workpieces; aligning a first gripper ofsaid end effector to a first of said plurality of workpieces; using asuction system, in communication with said first gripper to pick up saidfirst of said plurality of workpieces; aligning a second gripper of saidend effector to a second of said plurality of workpieces; and using asuction system, in communication with said second gripper to pick upsaid second of said plurality of workpieces while said first gripperholds said first of said plurality of workpieces.
 22. The method ofpicking up a plurality of workpieces of claim 21, further comprisingtransferring said first and second of said plurality of workpieces to aswap module, wherein said swap module moves said first and second ofsaid plurality of workpieces to a destination.